An estimated 170 million people worldwide have been infected by hepatitis C virus (HCV). In the next few years, the number of U.S. deaths for HCV-caused liver disease and cancer may overtake deaths caused by Acquired Immune Deficiency Syndrome (AIDS).
The transmission of HCV seems to require blood-to-blood contact. Carrying a single strand of ribonucleic acid (RNA), HCV contains just one gene, coding for a polyprotein that is subsequently cleaved into at least 10 functional proteins. Clearly, the ability to test the blood supply for HCV is of great importance. A sensitive assay that can detect infection at an early stage would be helpful.
HCV detection assays typically detect antibodies against HCV virus. These antibodies are detected in immunoassays using recombinant proteins and peptides containing HCV protein sequences. Most commercial anti-HCV assays use proteins from the following regions, core protein, NS3, NS4, and NS5 protein sequences.
Anti-HCV core antibodies are one of the most prevalent anti-HCV antibodies detected in chronic HCV infected individuals. HCV core protein contains multiple epitopes. Using synthetic peptides in the HCV core region, it has been shown that most of these epitopes are in the amino terminal end of this protein. For example, using overlapping peptides, each approximately 15 amino acids in length, an ELISA was developed to screen for anti-HCV antibodies in chronic HCV infected individuals. Table 1 below shows the peptide sequences. As shown in Table 2 below, HCV infected individuals have antibodies to two or more of these core peptides. Thus, it has been shown that the complete core peptide is not required to detect anti-core antibodies.
TABLE 1HCVPeptideAmino AcidPolyproteinID #SequenceAA Location0MSTNPKPQKKNKRNT 1-15SEQ ID NO.:1 1KNKRNTNRRPQDVKF10-24SEQ ID NO.:2 2QDVKFPGGGQIVGGV20-34SEQ ID NO.:3 3QIVGGVYLLPRRGPR29-43SEQ ID NO.:4 4RRGPRLGVPATRKTS39-53SEQ ID NO.:5 5ATRKTSERSQPRGRR48-62SEQ ID NO.:6 6PRGRRQPIPKARRPE58-72SEQ ID NO.:7 7KARRPEGRTWAQPGY67-81SEQ ID NO.:8 8AQPGYPWPLYGNEGC77-91SEQ ID NO.:9 9YGNEGCGWAGWLLSP 86-100SEQ ID NO.:10 10WLLSPRGSRPSWGPT 96-110SEQ ID NO.:11 11SWGPTDPRRRSRLNG106-120SEQ ID NO.:12 12SRLNGKVIDTLTCGF116-130SEQ ID NO.:13 13LTCGFADLMGYIPLV126-140SEQ ID NO.:14 14YIPLVGAPLGGAARA136-150SEQ ID NO.:15 15GAARALAHGVRVLED146-160SEQ ID NO.:16 16RVLEDGVNYATGNLP156-170SEQ ID NO.:17 17TGNLPGCSFSIFLLA166-180SEQ ID NO.:18
TABLE 2Peptide01234567891011121314151617Neg0.0440.0040.0210.0750.0590.0690.0760.1030.0200.0340.0020.0880.0510.0280.0230.0340.0410.042Neg0.0450.0650.0170.0810.0510.0810.1030.1110.0330.0350.0020.0850.0380.0300.0230.0300.0380.052Neg0.0500.0030.0140.0750.0870.0790.0940.1020.0250.0340.0020.0710.0380.0330.0210.0310.0390.047Neg0.0140.0430.1340.0230.0340.0390.0340.0390.0120.018−0.0010.0250.0090.0090.0080.0130.0100.020Neg0.0150.0390.1190.0210.0330.0300.0300.0340.0130.0190.0000.0260.0110.0100.0050.0120.0100.016Neg0.0130.0360.1260.0270.0530.0320.0370.0420.0130.0160.0010.0370.0130.0090.0090.0120.0090.017Neg0.0160.0040.1040.0200.0390.0340.0030.0410.0190.0190.0000.0410.0110.0170.0060.0100.0080.021 90.2562.5002.5000.4251.4430.0160.2180.2480.0620.0150.0250.0490.0300.0130.0120.0210.0120.028110.4132.5002.5000.9170.2290.6470.1140.2620.1660.1590.0020.0550.0220.0270.0210.0420.2470.088150.0440.6612.5000.0670.5770.0570.1100.0720.0610.032−0.0030.0450.0180.0310.0200.0390.0350.080181.6430.8872.5000.6410.1000.0520.0320.5760.0370.022−0.0010.0400.0060.0100.0090.0250.0360.039200.0210.1112.5002.5000.4820.0320.0290.0450.0280.0150.0110.0350.0090.0140.0090.0170.0190.059212.5002.5002.5002.2622.5000.5162.2590.0800.3780.0180.0220.0640.0130.0240.0170.0240.1350.035270.0322.5002.5000.0892.5001.6521.3490.0430.0390.0340.0330.0260.0120.0180.0130.0280.2870.008302.5002.5002.5002.5000.1830.0440.0750.9930.0780.0350.0280.1900.0230.0250.0220.0280.0420.043350.0220.2780.9120.0310.0360.1160.0790.0490.0620.0100.0050.0260.0050.0060.0090.0200.0070.020360.0590.1292.5000.0900.1310.0600.0930.1480.0900.0370.0030.0500.0180.0600.0770.0620.1290.079372.5002.5002.5000.2190.1300.0900.1690.2230.1470.0400.0180.0650.0160.0510.0510.0250.0800.110390.1652.5002.5002.5000.1241.2172.3512.5000.3970.0560.0151.3190.0170.0500.0560.0410.2000.190400.0582.5002.5002.5000.0980.0660.0600.7550.0930.0240.0000.0590.0130.0280.0170.0320.0680.101420.0220.0432.5000.0310.0230.1500.0180.0360.0230.011−0.0010.0320.0050.0140.0060.0100.0120.031430.1580.6120.3680.0330.0650.1030.0690.0750.0530.0510.0010.0550.0250.0220.0150.0230.0290.035440.0422.2402.5000.5110.0700.0600.0860.3010.1080.066−0.0020.1430.0280.0410.0280.0470.0610.076451.0022.5002.5000.1740.7130.0550.1291.7221.8960.029−0.0030.0690.0380.0380.0550.0220.1360.039460.0160.0312.5000.0220.0210.0210.0380.0350.0310.027−0.0020.0270.0160.0150.0130.0260.0190.037472.4842.5002.5000.4490.7500.5930.1022.0060.3310.017−0.0040.0340.0120.0140.0070.0260.0140.032480.4270.2012.5000.3640.3560.0380.0490.0700.0270.029−0.0010.0400.0180.0110.0130.0250.0140.095490.0190.4832.5000.0440.0450.0470.0500.2460.0390.025−0.0050.0330.0190.0140.0130.0300.0160.085500.6682.5002.5000.5681.2330.2770.1542.5000.8820.024−0.0010.0350.0140.0120.0070.0170.0440.055522.5002.5002.5000.9481.1161.6190.0260.2670.1120.0190.0260.0420.0120.0070.0090.0190.0080.044530.8232.5002.5000.4282.5000.7800.0862.5001.5660.0250.0010.0500.0140.0200.0110.0220.0190.028541.5772.5002.5002.5002.5002.5002.5002.5002.5000.0200.0320.0530.0210.0120.0120.0200.0170.038550.0170.0832.5000.0470.0180.0230.0710.0420.0190.017−0.0020.0260.0150.0150.0120.0260.0140.030582.5002.5002.5002.2832.5002.5002.5002.5000.8100.0370.0730.0670.0180.0190.0210.0250.1590.059590.0151.8052.5000.0232.5000.0190.1800.0380.0700.0390.0270.0170.0120.0150.0180.0150.0230.049600.0532.5002.5000.2552.5000.1021.2660.6662.5000.034−0.0030.1530.0260.0190.0220.0390.0970.063620.0180.0532.5001.1780.0250.0310.0410.0600.0280.017−0.0020.0390.0130.0120.0100.0170.0100.048630.0090.0160.0270.0120.0170.0131.2250.0280.0120.017−0.0040.0260.0070.0070.0060.0100.0570.020651.4400.0410.0260.0400.0320.0560.0520.0620.0200.0400.0230.0510.0180.0230.0230.0190.0200.035662.0602.5002.5001.0302.5000.5080.1442.5002.5000.0130.0090.0600.0070.0090.0090.0140.0250.018672.5002.5002.5002.5002.5001.3380.4062.5000.1350.0310.0030.0910.0210.0270.0280.0320.0420.077682.5002.5002.5001.1050.4150.3581.0252.5000.2630.0280.0060.0390.0230.0250.0220.0240.0340.037700.7452.5002.5000.3422.5000.2000.0490.0751.7300.0300.0090.1190.0150.0250.0220.0270.0560.050730.0312.3922.5000.0490.6290.9350.5961.1190.0810.0400.0090.0520.0280.0360.0310.0380.0430.059750.0372.5002.5001.4351.3420.1070.2870.0940.0800.0490.0120.0310.0130.0300.0170.0210.0580.050782.5002.5002.5000.2692.5000.2980.0512.5000.0400.0570.0060.0840.0130.0220.0140.0210.0220.030800.2802.5002.5000.6740.3180.9720.0482.1180.0400.0210.0220.0240.0150.0100.0080.0140.0660.031840.0120.0752.5000.0250.1900.1450.1060.0990.0190.0280.0500.0180.0090.0100.0090.0130.0090.026900.0190.3062.5000.0392.5000.6890.0330.3010.1950.0210.0050.0330.0110.0170.0100.0130.0140.018
A recent report indicates that the HCV core protein can be detected in HCV infected individuals before the appearance of anti-HCV antibodies. (S. Lee et al., Vox Sanguinis, 2001; 80: 19-23). Therefore, we suggest that a more efficient way of early detection of HCV infection would be a combination assay able to detect HCV core protein and anti-HCV antibodies including anti-core antibodies.